Device, system and method for detecting a direction of gaze based on a magnetic field interaction

ABSTRACT

Techniques and mechanisms for determining a direction of gaze by a user of an ophthalmic device. In an embodiment, at least a portion of a magnetic field is generated by one of the ophthalmic device and an auxiliary reference device while the ophthalmic device is disposed in or on an eye of the user, and while the auxiliary reference device is adhered on the user&#39;s skin or under a surface of the skin. The ophthalmic device and the auxiliary reference device interact with each other via a magnetic field, and the interaction is detected with one or more sensors of the ophthalmic device. In another embodiment, the ophthalmic device stores predetermined reference information which corresponds various magnetic field signal characteristics each with a different respective direction of gaze. Based on the sensor information and the reference information, a controller of the ophthalmic device determines a direction in which the eye of the user is gazing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/303,311, filed on Mar. 3, 2016, the entire contents of which arehereby incorporated by reference herein.

BACKGROUND

1. Technical Field

This disclosure relates generally to the field of optics, and inparticular but not exclusively, relates to contact lenses.

2. Background Art

Accommodation is a process by which the eye adjusts its focal distanceto maintain focus on objects of varying distance. Accommodation is areflex action, but can be consciously manipulated. Accommodation iscontrolled by contractions of the ciliary muscle. The ciliary muscleencircles the eye's elastic lens and applies a force on the elastic lensduring muscle contractions that change the focal point of the elasticlens.

As an individual ages, the effectiveness of the ciliary muscle degrades.Presbyopia is a progressive age-related loss of accommodative orfocusing strength of the eye, which results in increased blur at neardistances. This loss of accommodative strength with age has been wellstudied and is relatively consistent and predictable. Presbyopia affectsnearly 1.7 billion people worldwide today (110 million in the UnitedStates alone) and that number is expected to substantially rise as theworld's population ages.

Recent technologies have begun to provide for various devices thatoperate in or on a human eye to aid the visual focus of a user. For sometypes of these devices, an accommodating lens includes one or moreelements and circuitry to apply an electrical signal to change afocusing power of the one or more elements. Determining when to changesuch focusing power is often based on a direction of a gaze by a user ofthe optical device. As the capabilities of accommodation-capable opticaldevices continue to increase, there is expected to be an increaseddemand for such optical devices to provide accurate tracking ofdirection of gaze by a user.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments of the present invention are illustrated by wayof example, and not by way of limitation, in the figures of theaccompanying drawings and in which:

FIG. 1 is a functional block diagram illustrating elements of a systemto determine a direction of gaze by a user of an ophthalmic deviceaccording to an embodiment.

FIG. 2 is a flow diagram illustrating elements of a method to determinea direction of gaze by a user of an ophthalmic device according to anembodiment.

FIG. 3 shows various views each of a respective system to determine adirection of gaze by a user of an ophthalmic device according to acorresponding embodiment.

FIGS. 4A, 4B and 4C show elevation views each of a respective system todetermine a direction of gaze by a user of an ophthalmic deviceaccording to a corresponding embodiment.

FIG. 5 is a functional block diagram of an ophthalmic device forauto-accommodation along with an external reader, in accordance with anembodiment of the disclosure.

FIG. 6A is a top view of an ophthalmic device, in accordance with anembodiment of the disclosure.

FIG. 6B is a perspective view of an ophthalmic device, in accordancewith an embodiment of the disclosure.

FIG. 7 is a cross-sectional illustration of an eye with an implantedintraocular device to detect gaze direction in accordance with oneembodiment.

DETAILED DESCRIPTION

Embodiments described herein variously provide an apparatus, systemand/or method for determining a direction of gaze by a user of anophthalmic device. In the following description numerous specificdetails are set forth to provide a thorough understanding of theembodiments. One skilled in the relevant art will recognize, however,that the techniques described herein may be practiced without one ormore of the specific details, or with other methods, components,materials, etc. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringcertain aspects.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

Certain features of various embodiments are described herein withreference to mechanisms and techniques for determining a direction ofgaze by a user of an eye-mountable device (EMD) that is mountable as acontact lens and that provides functionality to automatically provideany of various levels of accommodation. However, such discussion may beextended to additionally or alternatively apply to any of a variousother types of ophthalmic device. For example, an ophthalmic deviceaccording to some embodiments may include an intraocular lens (IOL) thatis implantable in an eye and/or may support other functionality inaddition to (or instead of) automatic accommodation.

An accommodation-capable ophthalmic device may assist viewing by a userwith a condition such as presbyopia or a cataract. An amount ofaccommodation to be provided by such an ophthalmic device may bedetermined based at least in part on a direction of gaze by the user ofthe ophthalmic device. For example, a higher level of accommodation maybe needed when the direction of gaze (corresponding to the eye'sorientation in the user's skull) is relatively high in the user's fieldof view. By contrast, a relatively low level of accommodation may beneeded when the direction of gaze is lower in the user's field of viewand/or is oriented more toward the nose bone of the skull.

In some embodiments, the direction of gaze is determined based on aninteraction between the ophthalmic device and another device (referredto herein as an “auxiliary reference device”) that is adhered on orimplanted in the user. Such an auxiliary reference device may be fixedrelative to the user's skull, and may move relative to the user's eyeand relative to the ophthalmic device disposed in or on the eye. Anauxiliary reference device according to one embodiment includes amechanism, such as a magnet or a coil, that can generate, or otherwiseaffect the generation of, a magnetic field that is sensed by one or moremagnetic sensors of the ophthalmic device. Interaction with theauxiliary reference device via the magnetic field may enable theophthalmic device to detect a position and/or an orientation of theophthalmic device relative to the auxiliary reference device (and thus,relative to the user's skull).

For example, the ophthalmic device may include or otherwise have accessto pre-determined reference information that corresponds variouscharacteristics of magnetic field signals (for brevity, ‘magnetic fieldsignal characteristics’ herein) each with a respective state of theophthalmic device and/or the auxiliary reference device. Such magneticfield signal characteristics may include characteristics of one or moresignal to generate the magnetic field and/or characteristics of one ormore signal generated based on the magnetic field. The ophthalmic devicemay access the reference information, based on output from a magneticsensor of the ophthalmic device, to identify a position and/ororientation of the ophthalmic device relative to the auxiliary referencedevice. Based on the identified position and/or orientation, theophthalmic device may control operation of an accommodation actuatorand/or other mechanism.

FIG. 1 illustrates features of a system 100 to detect a direction ofgaze according to an embodiment. System 100 includes devices that areeach to be variously disposed in or on the body of a user, whereinteraction between such devices via one or more magnetic fields is tofacilitate detection of a direction of gaze by that user. Unlessotherwise indicated, “auxiliary reference device,” “reference device,”“reference unit” and similar terms refer to a mechanism, such as that ofan auxiliary reference device 120 of system 100, that operates tointeract with an ophthalmic device via a magnetic field, wherein adirection of gaze is determined based on such interaction. An auxiliaryreference device external to the ophthalmic device, or a componentthereof, may serve as a reference for detecting a direction ofgaze—e.g., relative to some baseline gaze direction. An auxiliaryreference device may comprise a magnetic source configured to bepositioned on or under the user's skin—e.g., peripherally to an eye ofthe user. The auxiliary reference device may thus have a fixed position,relative to the skull of the user, at least during a period of timeduring which the user's eye moves (along with an ophthalmic devicedisposed therein or thereon) within an orbital socket of the skull. Theposition of the ophthalmic device relative to the auxiliary referencedevice may thus correspond to an orientation of the user's eye withinthe skull. This relative position (and/or a change in such a relativeposition) may provide a basis for determining a direction of gaze by theuser.

In the illustrative embodiment shown, system 100 includes an ophthalmicdevice 110 that is (or is configured to be) disposed in or on a user'seye (not shown). For example, an enclosure 116 of device 110 may form abiocompatible exterior to accommodate such disposition in or on the eye.System 100 may further comprise one or more other devices—e.g.,including the illustrative auxiliary reference device 120—each of whichis (or is configured to be) disposed on or under the user's skin.Ophthalmic device 110 may include a contact lens, or an intraoculardevice, comprising integrated circuitry, encapsulated by enclosure 116,to facilitate detection of a direction of gaze. Such integratedcircuitry may include one or more magnetic sensors (such as theillustrative sensor 112 shown) and a controller 114. Sensor 112 mayoperate to detect one or more characteristics of a magnetic field 130between ophthalmic device 110 and auxiliary reference device 120 (e.g.,where magnetic field 130 is concurrent with and overlaps one or moreother magnetic fields). Alternatively or in addition, sensor 112 maysense one or more characteristics of signaling to generate at least aportion of magnetic field 130. Based on sensor information output bysensor 112, controller 114 may determine a direction of gaze by an eyein which or on which is disposed ophthalmic device 110.

For example, controller 114 may comprise logic (e.g.,application-specific integrated circuitry, executable instructionsand/or the like) that, when executed, causes the controller 114 tomeasure, with one or more magnetic sensors such as sensor 112, amagnetic field interaction between the ophthalmic device 110 andauxiliary reference device 120. Such measuring may include generatingmagnetic field 130 with an electromagnet circuit of ophthalmic device110—e.g., wherein the magnetic field interaction is measured as a loadon the electromagnet circuit. The one or more magnetic sensors may beoperated by controller 114 to generate one or more magnetic fieldsignals in response to such measuring of the magnetic field interaction.In some embodiments, controller 114 operates to monitor the one or moremagnetic field signals and to correlate the one or more magnetic fieldsignals to a gazing direction of ophthalmic device 110.

For example, controller 114 may include or otherwise have access topre-determined reference information (not shown) that correspondsvarious sets of sensor information each with a different respectiveconfiguration of ophthalmic device 110 and auxiliary reference device120 relative to each other. Some or all configurations may each include,for example, a respective distance between ophthalmic device 110 andauxiliary reference device 120 and/or a respective angular offsetbetween ophthalmic device 110 and auxiliary reference device 120.

Controller 114 may include logic operable to output one or moresignals—based, for example, on information from sensor 112 andpredetermined reference information—identifying or otherwise indicatingan angular offset of the gaze direction from some reference direction.Such one or more signals may indicate the direction of gaze byidentifying a distance and/or an angular offset between respectivecomponents of ophthalmic device 110 and auxiliary reference device120—e.g., with respect to the illustrative x, y, z coordinate systemshown. In an embodiment, signaling output by controller 114 is used tocontrol an automatic accommodation and/or some other functionality thatis provided by ophthalmic device 110.

Auxiliary reference device 120 is one example of an embodiment that maybe disposed on or under the skin of a user of ophthalmic device 110 (orof some other user of an ophthalmic device). By way of illustration andnot limitation, auxiliary reference device 120 may include a capsule oran adhesive bandage. Interaction with ophthalmic device 110 via magneticfield 130 may occur while auxiliary reference device 120 is within 1 cmof a surface of the user's skin—e.g., while auxiliary reference device120 is also in a fixed position relative to the user's skull. Auxiliaryreference device 120 may be small enough and/or light enough to beimperceptible by the user of ophthalmic device 100. An overall weight ofauxiliary reference device 120 may be equal to or less than 1 ounce, forexample. Alternatively or in addition, a total volume of auxiliaryreference device 120 may be equal to or less than 1 cm³—e.g., where sucha volume is equal to or less than 500 mm³ and, in some embodiments,equal to or less than 250 mm³. In some embodiments, auxiliary referencedevice 120 has a maximum width (e.g., a diameter) that is equal to orless than 2.5 cm—e.g., where the maximum width is equal to or less than2.0 cm and, in some embodiments, equal to or less than 1 cm.Alternatively or in addition, a smallest side of auxiliary referencedevice 120 may have a length that is equal to or less than 5 mm—e.g.,where the smallest side is equal to or less than 2 mm. In someembodiments, the smallest side is equal to or less than 1 mm (e.g.,equal to or less than 500 um). Alternatively or in addition, a maximumcross-sectional area of auxiliary reference device 120 may be equal toor less than 4 cm², for example. Such a maximum cross-sectional area maybe equal to or less than 3 cm² and, in some embodiments, equal to orless than 2 cm². However, such weights and dimensions of auxiliaryreference device 120 are merely illustrative, and not limiting on otherembodiments.

Auxiliary reference device 120 may omit some functionality that isprovided by one or more other devices that are included in, or are tooperate with, system 100. For example, in one embodiment, any userinterface mechanism (e.g., including any display, any microphone and/orany speaker) of system 100 is provided by one or more devices other thanauxiliary reference device 120. Alternatively or in addition, any opticsof system 100 may be provide by one or more devices other than auxiliaryreference device 120. In one embodiment, any communication betweenauxiliary reference device 120 and ophthalmic device 110 (or betweenauxiliary reference device 120 and any other device, for example) isonly via wireless signaling.

The illustrated embodiment of auxiliary reference device 120 includes anenclosure 122 (or other housing structure) having disposed therein amechanism, illustrated as reference unit 124, that is to serve as areference for determining a relative position and/or a relativeorientation of ophthalmic device 110. Enclosure 122 may be at leastpartially transparent to electromagnetic energy, thus allowing one ormore components of reference unit 124 to generate or interact with atleast some component of the magnetic field 130 that extends betweenophthalmic device 110 and auxiliary reference device 120.

In one embodiment, enclosure 122 includes any of a variety ofbiocompatible materials that facilitate implantation (e.g., subcutaneousinjection) of auxiliary reference device 120 within the body of a userof ophthalmic device 110. By way of illustration and not limitation,enclosure 122 may include any of various polyimide, parylene, silicone,ceramic and/or other materials adapted from conventional implantablemedical device technologies. In another illustrative embodiment,auxiliary reference device 120 is to be disposed on a surface of theuser's skin. For example, enclosure 122 may include a flexiblematerial—such as a woven fabric, a plastic (such as polyethylene orpolyurethane), latex or other such material—and a coating comprising anacrylate, resin or other such adhesive for applying auxiliary referencedevice 120 onto an exterior surface of the user's skin.

Reference unit 124 illustrates any of a variety of mechanisms togenerate or to interact with at least a portion of magnetic field 130.For example, reference unit 124 may include a permanent magnet and/or anelectromagnet circuit (e.g., including a solenoid) to generate at leasta portion of magnetic field 130. In such an embodiment, sensor 112 mayoperate to detect a strength and/or a direction of such a portion ofmagnetic field 130. A permanent magnet of reference unit 124 mayinclude, for example, Neodymium (Nd), samarium-cobalt (SmCo) and/or anyof a variety of other materials adapted from conventional techniques forgenerating a magnetic field.

Alternatively or in addition, one or more components (not shown) ofophthalmic device 110 may instead, or also, generate at least part ofmagnetic field 130. For example, ophthalmic device 110 may itselfinclude a permanent magnet and/or an electromagnet circuit. In such anembodiment, reference unit 124 may include a circuit structure (e.g.,including an antenna) that interacts with one or more components ofmagnetic field 130 that are generated by ophthalmic device 110. Suchinteraction may include coupling whereby the circuit structure ofreference unit 124 functions as a load on the generation of magneticfield components by ophthalmic device 110. By way of illustration andnot limitation, reference unit 124 may include an antenna to couple withat least a portion of magnetic field 130, the antenna including aconductor forming a coil, helix, logarithmic spiral and/or any ofvarious other shapes. Such a conductor may include a non-ferromagneticmetal forming a microcoil, or other such structure.

In some embodiments, such an antenna includes any of various shortdipole antenna structures, near field antenna structures and/or thelike. As used herein, “antenna” refers to any structure that can operateto perform one or both of radiating an electromagnetic field andcoupling to an electromagnetic field. This includes, for example, any ofa variety of structures that facilitate a reactive exchange ofenergy—e.g., in addition to, any exchange of energy by electromagneticradiation.

Reference unit 124 may interact with magnetic field 130 using only oneor more passive circuit structures. For example, circuit structures ofreference unit 124 may omit any transistors or other active circuitelements. Such one or more passive circuit structures may be energizedusing only a power source that is external to auxiliary reference device120 (e.g., where such a power source is a component of ophthalmic device110). In other embodiments, reference unit 124 (or some other componentof auxiliary reference device 120) includes integrated circuitry tofacilitate interaction with ophthalmic device 110 via magnetic field130. By way of illustration, such integrated circuitry may modulate thegeneration of, or an interaction with, some component of magnetic field130. Alternatively or in addition, such integrated circuitry mayfacilitate wireless communication between auxiliary reference device 120and ophthalmic device 110 (and/or some other device, not shown).

FIG. 2 illustrates elements of a method 200, according to an embodiment,to detect a direction of gaze by a user of an ophthalmic device. Method200 may include operations performed with some or all components ofsystem 100, for example. In one embodiment, method 200 is performed by adevice having some or all of the features of ophthalmic device 110. Toillustrate certain features of various embodiments, method 200 isdescribed herein with reference to a system 300 that is shown in FIG. 3.However, such discussion may be extended to additionally oralternatively apply to any of a variety of other devices and/or systemsof devices, according to different embodiments. Some or all of system300 may, in various embodiments, provide functionality that isalternative to and/or in addition to that provided according to method200.

In an embodiment, method 200 includes, at 210, measuring a magneticfield interaction between an ophthalmic device and an auxiliaryreference device (e.g., between ophthalmic device 110 and auxiliaryreference device 120). The magnetic field interaction may take place viaa magnetic field, such as field 130, which extends outside of theophthalmic device in a region between the ophthalmic device and theauxiliary reference device. The magnetic field interaction (and themeasuring thereof at 210) may occur while the auxiliary reference deviceis adhered onto, or disposed under a surface of, the skin of auser—e.g., while the ophthalmic device is disposed in or on an eye ofthat user.

Method 200 may further comprise, at 220, generating one or more magneticfield signals in response to the measuring at 210. As used herein,‘magnetic field signal’ refers to a signal—e.g., including a voltagesignal or a current signal—which is generated based on a sensing of amagnetic field, wherein the signal specifies or otherwise indicates acharacteristic of the magnetic field. One or more magnetic field signalsmay, for example, indicate any of a variety of combinations of one ormore static conditions and/or one or more dynamic conditions including,but not limited to, a magnitude, direction, rate of change, modulation,etc. of a magnetic field.

In the illustrative embodiment of FIG. 3, system 300 includes anophthalmic device OD 314 disposed in or on an eye of a user 310 usingsystem 100. The other eye of user 310 may also have another ophthalmicdevice (not shown) disposed therein or thereon. OD 314 may providefunctionality such as that of ophthalmic device 110 or any of variousother ophthalmic devices described herein. For example, system 300 mayfurther comprise an auxiliary reference device RD 312 that is configuredto remain in a fixed orientation relative to the head of user 310—e.g.,at least while user 310 is variously viewing in different directionswith OD 314 at different times. During such viewing, one of RD 312 andOD 314 may generate at least part of a magnetic field that extends intosome region including the other of RD 312 and OD 314. One or moremagnetic sensors (not shown) of OD 314 may determine, based the magneticfield and/or signaling to create the magnetic field, a direction of gazeby the eye of user 310. For example, a magnet or a circuit structure ofRD 312 may interact with ophthalmic device 312 via such a magnetic fieldwhile ophthalmic device 312 is disposed in or on the eye of user 310,and also while RD 312 is adhered onto, or disposed under a surface of,the skin of user 310. In one embodiment, RD 312 is configured tointeract with ophthalmic device 312 while within 2 cm of the eye inwhich (or on which) is disposed ophthalmic device 312. For example, RD312 may be within 1 cm of the eye during interaction of RD 312 with OD314.

In one embodiment shown by the detail view in inset 320, aneye-mountable device EMD 340 (e.g., OD 314) is disposed on an eye 330.EMD 340 may be configured to interact with an auxiliary reference device(not shown) via a magnetic field B that is generated at least in part bythe auxiliary reference device or by a component of EMD 340. In anexample embodiment, an enclosure material of EMD 340 has formed thereina signal line 342 in which other circuitry (not shown) of ophthalmicdevice 342 is to drive a current. EMD 340 may further comprise one ormore sensors to measure a current, voltage and/or other signalcharacteristic based on signal line 342 conducting the current withinmagnetic field B.

By way of illustration and not limitation, a current in signal line 342,in combination with magnetic field B, may results in a Hall effectsensor 344 of EMD 340 exhibiting a voltage difference—e.g., along a lineof a direction that is orthogonal to a direction of the current insignal line 342. Sensor information generated with Hall effect sensor344—such as the one or more magnetic field signals generated at 220—mayindicate a direction, strength and/or any of various othercharacteristics of magnetic field B (e.g., including a change, rate ofchange, etc. of a characteristic). In some embodiments, the EMD 340includes an accommodation actuator (not shown)—e.g., wherein signal line342, an electromagnet circuit and/or other such magnetic sensor circuitstructure forms one or more loop structures which extend around some orall of a periphery of the accommodation actuator.

Method 200 may further comprise, at 230, correlating the one or moremagnetic field signals generated at 220 to a gazing direction. Forexample, the correlating at 230 may include accessing or otherwisedetermining reference information which corresponds various magneticfield signal characteristics each with a different respective directionof gaze. The reference information may be provided, for example, as an apriori input to the ophthalmic device prior to a sensing of a gazedirection with the ophthalmic device. In some embodiments, thedetermining at 210 includes performing a configuration operation tocalibrate a gaze detection functionality.

The correlating at 230 may include generating, based on a characteristicof the one or more magnetic field signals and further based onpredefined reference information, one or more signals describing adirection of gaze by a user of the ophthalmic device. For example, thecorrelating at 230 may include performing a search of the referenceinformation to identify, from among different magnetic field signalcharacteristics (e.g., different sets of magnetic field signalcharacteristics), those one or more magnetic field signalcharacteristics that most closely match the one or more magnetic fieldsignals generated at 220. The correlating at 230 may further compriseselecting the direction of gaze which is identified by the referenceinformation as corresponding to the most closely matching one or moremagnetic field signal characteristics. In the illustrative embodimentshown in inset 320, reference information (not shown) stored at EMD 340may be searched or otherwise processed by evaluation logic a controllerof EMD 340 to select, calculate or otherwise determine a direction ofgaze that most closely corresponds to the or more characteristics ofmagnetic field B that are detected with Hall effect sensor 344.

In an embodiment, method 200 further comprises, at 240, detecting, inreal-time, changes in the gazing direction based upon changes in the oneor more magnetic field signals. For example, controller logic of theophthalmic device may operate to monitor the one or more magnetic fieldsignals over time. Such monitoring may include or otherwise be based ona measuring the magnetic field interaction as a load on an electromagnetcircuit of the ophthalmic device. In such an embodiment, method 200 maycomprise modulating the magnetic field to induce the load. For example,the ophthalmic device may deliver energy via the magnetic field to powera modulation of the magnetic field by circuitry of the auxiliaryreference device.

Although some embodiments are not limited in this regard, method 200 mayfurther comprise operations (not shown) to provide an accommodationlevel with the ophthalmic device based on the gazing direction. Forexample, such operations may include electrically manipulating anaccommodation lens of the ophthalmic device to automatically change anoptical power of the ophthalmic device in response to the detecting at240. Such electrical manipulating may include one or more processesthat, for example, are adapted from conventional techniques and/ormechanisms which identify one of a plurality of gazing directions ascorresponding to a particular optical power to be provided with anaccommodation lens. The particular details of such conventionaltechniques and mechanisms are not detailed herein to avoid obscuringfeatures of various embodiments.

The correlating at 230 may include, or otherwise be based on, acalibration, training or other initial configuration process—e.g., todetermine magnetic field signal characteristics that are to be variouslyassociated each with one of a baseline (or reference) direction of gazeand various degrees and/or types of deviation from that baselinedirection of gaze. Such a configuration process may further determine,for each of various gaze directions other than the baseline, arespective one or more magnetic field signal characteristics that areindicative of that corresponding gaze direction.

By way of example and not limitation, such a configuration process mayinclude configuration hardware, software and/or other such logic—e.g.,included in a laptop, mobile device, or other external hardware (notshown) that communicates wirelessly with OD 314—operating to displaysome sequence of visual targets to user 310 while OD 314 and RD 312interact via a magnetic field. The configuration logic may prompt user310—e.g., through visual and/or audio output—to variously view suchtargets at different times, where the targets each have a knownposition, distance (depth) from user 310 and/or the like. In response,user 310 may provide to the calibration logic input (e.g., via amicrophone, handheld device or the like) variously indicating when suchtargets are being viewed. The calibration target may continuously moveto different positions, where user 310 indicates by a button press,verbal and/or other means when they are or are not visually tracking themoving target.

In some embodiments, two (or more) auxiliary reference devices may bearranged in a configuration that is fixed, relative to the skull of auser, and that enables such auxiliary reference devices to participatein different respective magnetic interactions with the same ophthalmicdevice. One or more magnetic sensors of the ophthalmic device mayvariously detect signal characteristics that are variously based each ona respective one of such interactions. A controller of the ophthalmicdevice may process the output of the one or more magnetic sensors,wherein the two or more auxiliary reference devices are used as multiplereferences for detecting a relative position of the ophthalmic device(and a corresponding direction of gaze by a user of the ophthalmicdevice).

For example, method 200 may further comprise the ophthalmic devicemeasuring, with one or more magnetic sensors, a second magnetic fieldinteraction between the ophthalmic device and a second auxiliaryreference device which is also external to the ophthalmic device. Theone or more magnetic sensors may further generate a second one or moremagnetic field signals based on the second magnetic field interaction.In such an embodiment, the correlating at 230 may include correlating acombination of both the one or more magnetic field signals (generated at220) and the second one or more magnetic field signals to the gazingdirection.

By way of illustration and not limitation, as shown in inset 360 of FIG.3, one embodiment may include an ophthalmic device 380 configured to bedisposed in or on an eye 372—e.g., where ophthalmic device 380 is acontact lens to cover some or all of an iris 374 of eye 372 and that maybe partially overlapped by an eyelid 370. Inset 360 illustrates someexamples of locations 390 (on or under a surface of the user's skin)where such one or more auxiliary reference devices—e.g., including RD312—might be variously located. However, the one or more auxiliaryreference devices may be located in more, fewer and/or differentlocations near (e.g., within 2 cm) of eye 372. A range of possiblelocations of ophthalmic device 380 during movement of eye 372 may allowfor interaction between ophthalmic device 380 and one or more auxiliaryreference devices that are each disposed on or under a surface of theskin of the user. In an embodiment, ophthalmic device 380 includes oneor more magnetic sensors—e.g., including the illustrative magneticsensor 382—to detect interactions between ophthalmic device 380 andmultiple auxiliary reference devices variously disposed each at adifferent respective one of the locations 390.

In one embodiment, ophthalmic device 380 includes circuitry thatoperates to determine a correspondence of auxiliary reference deviceseach with a different respective magnetic field or magnetic fieldresponse. By way of illustration and not limitation, a memory (notshown) of ophthalmic device 380 may store additional referenceinformation that defines resonant frequencies and/or other signalcharacteristics that are to variously serve as signatures each of adifferent respective auxiliary reference device. Such signatures may beused by a controller of the ophthalmic device to distinguish a magneticfield interaction involving one auxiliary reference device from anothermagnetic field interaction involving a different auxiliary referencedevice. In distinguishing such interactions from one another, ophthalmicdevice 380 may determine a direction of gaze by eye 372 by performingcalculations to triangulate a position and/or an orientation ofophthalmic device 380 relative to multiple auxiliary reference devices.

FIG. 4A illustrates features of a system 400 to determine a direction ofgaze according to an embodiment. System 400 may include features ofsystem 100 and/or system 300, for example. In an embodiment, operationof system 400 is performed according to method 200. System 400 includesan ophthalmic device 410 and an auxiliary reference device 420 that areto interact with one another via a magnetic field 402. Based on suchinteraction, ophthalmic device 410 may determine a direction of gaze bya user of ophthalmic device 410.

In the illustrative embodiment of system 400, auxiliary reference device420 generates some or all of magnetic field 402. For example, magneticfield 402 may include at least some non-varying component that isprovide by a permanent magnet of auxiliary reference device 420.Alternatively or in addition, auxiliary reference device 420 may includean electromagnet circuit (e.g., comprising a solenoid) that operates toprovide some or all of magnetic field 402. Such an electromagnet circuitmay modulate one or more components of magnetic field 402—e.g., wheresuch modulation is to serve as a signature for distinguishing auxiliaryreference device 420 from one or both of a background magnetism of thesurrounding environment and any magnetic field signature of some otherdevice (not shown). Although some embodiments are not limited in thisregard, operation of such an electromagnetic circuit may be powered byan energy harvesting antenna (not shown) of auxiliary reference device420. Such an energy harvesting antenna may be powered, for example, bysignals from ophthalmic device 410 or from some other device (not shown)that is included in or operates with system 400.

A magnetic sensor 412 of ophthalmic device 410 may provide to acontroller (not shown) of ophthalmic device 410 sensor informationindicating a direction, strength and/or other characteristic of field402. For example, magnetic sensor 412 may include one or more Halleffect sensors, a magnetic coupling detector, a giant magnetoresistance(GMR) sensor and/or any of a variety of other mechanisms adapted fromconventional techniques for detecting a characteristic of a magneticfield and/or characteristics of signaling to generate a magnetic field.The details of such conventional techniques are not limiting on someembodiments, and are not detailed herein to avoid obscuring features ofvarious embodiments.

FIG. 4B illustrates another system 430 to determine a direction of gazeaccording to a different embodiment—e.g., where system 430 is analternative embodiment to that of system 410. System 430 includes anophthalmic device 440 and an auxiliary reference device 450 that are tointeract with one another via a magnetic field 432. Based on suchinteraction, ophthalmic device 440 may determine a direction of gaze bya user of ophthalmic device 440. In the illustrative embodiment ofsystem 430, a magnetic field generator 442 of ophthalmic device 440provides some or all of magnetic field 402. For example, magnetic fieldgenerator 442 may include an electromagnet circuit. A passive circuitstructure 452 of auxiliary reference device 450 may couple with magneticfield 402—e.g., the passive circuit structure 452 including an antennastructure such as a micro-coil. For example, auxiliary reference device450 may interact with magnetic field 432 only via passive circuitelements, conductors and/or the like. Such coupling may serve as a loadon an electromagnet circuit of magnetic field generator 442. The loadmay be detected with a magnetic sensor 444 of ophthalmic device 410,where such detection aids in determining a position of auxiliaryreference device 450 relative to ophthalmic device 410.

FIG. 4C illustrates a system 460 to determine a direction of gazeaccording to another embodiment—e.g., where system 460 is an alternativeembodiment to one of systems 410, 430. System 460 includes an ophthalmicdevice 470 and an auxiliary reference device 480 that are to interactwith one another via a magnetic field 462. Based on such interaction,ophthalmic device 470 may determine a direction of gaze by a user ofophthalmic device 470. In system 460, a magnetic field generator 472 ofophthalmic device 470 provides some or all of magnetic field 402. Anantenna 482 of auxiliary reference device 480 may couple with magneticfield 402. Such coupling may be varied over time by a control circuit480 of auxiliary reference device 480. For example, control circuit 480may include integrated circuitry comprising active circuit elements thatare powered by magnetic field 432 (and/or some other remote source ofelectromagnetic energy) to modulate coupling of antenna 482 withmagnetic field 432. Such coupling may serve as a time-varying load on anelectromagnet circuit of magnetic field generator 472, which may bedetected with a magnetic sensor 474 of ophthalmic device 410. Suchdetection may in turn aid in a controller (not shown) of EMD 410determining a position of auxiliary reference device 480 relative to EMD410.

FIG. 5 is a functional block diagram of an accommodation-capableeye-mountable device 500 to be accessed via an auxiliary device 505, inaccordance with an embodiment. EMD 500 may include some or all featuresof one of ophthalmic devices 110, 314, 410, 430, 460, for example. Anexposed portion of EMD 500 may include an enclosure material 510 formedto be contact-mounted to a corneal surface of an eye. A substrate 515may be embedded within or surrounded by enclosure material 510 toprovide a mounting surface for a power supply 520, a controller 525, anaccommodation actuator 530, a sensor system 535, an antenna 540, andvarious interconnects 545 and 550. The illustrated embodiment of powersupply 520 includes an energy harvesting antenna 555, charging circuitry560, and a battery 565. The illustrated embodiment of controller 525includes control logic 570, accommodation logic 575, and communicationlogic 580. The illustrated embodiment of auxiliary device 505 includes aprocessor 582, an antenna 584, and memory 586. The illustratedembodiment of memory 586 includes data storage 588 and programinstructions 590.

Controller 525 may be coupled to receive feedback control signals fromsensor system 535 and further coupled to operate accommodation actuator530. Sensor system 535 may provide functionality such as that of one ofsensors 112, 382, 412, 444, 474, for example. Power supply 520 suppliesoperating voltages to the controller 525 and/or the accommodationactuator 530. Antenna 540 may be operated by the controller 525 tocommunicate information to and/or from eye-mountable device 500. In oneembodiment, antenna 540, controller 525, power supply 520, and sensorsystem 535 are all situated on the embedded substrate 515. In oneembodiment, accommodation actuator 530 may be embedded within enclosurematerial 510, but is not disposed on substrate 515. Becauseeye-mountable device 500 includes electronics and is configured to becontact-mounted to an eye, it is also referred to herein as anophthalmic electronics platform, contact lens, or smart contact lens.

To facilitate contact-mounting, the enclosure material 510 may have aconcave surface configured to adhere (“mount”) to a moistened cornealsurface (e.g., by capillary forces with a tear film coating the cornealsurface). Additionally or alternatively, the eye-mountable device 500may be adhered by a vacuum force between the corneal surface andenclosure material 510 due to the concave curvature. While mounted withthe concave surface against the eye, the outward-facing surface of theenclosure material 510 may have a convex curvature that is formed to notinterfere with eye-lid motion while the eye-mountable device 500 ismounted to the eye. For example, the enclosure material 510 may be asubstantially transparent curved disk shaped similarly to a contactlens.

Enclosure material 510 may include one or more biocompatible materials,such as those employed for use in contact lenses or other ophthalmicapplications involving direct contact with the corneal surface.Enclosure material 510 may optionally be formed in part from suchbiocompatible materials or may include an outer coating with suchbiocompatible materials. Enclosure material 510 may include materialsconfigured to moisturize the corneal surface, such as hydrogels and thelike. In some instances, enclosure material 510 may be a deformable(“non-rigid”) material to enhance wearer comfort. In some instances,enclosure material 510 may be shaped to provide a predetermined,vision-correcting optical power, such as can be provided by a contactlens. Enclosure material may be fabricated of various materialsincluding a polymeric material, a hydrogel, PMMA, silicone basedpolymers (e.g., fluoro-silicon acrylate), or otherwise.

Substrate 515 includes one or more surfaces suitable for mounting thesensor system 535, controller 525, power supply 520, and antenna 540.Substrate 515 may be employed both as a mounting platform for chip-basedcircuitry (e.g., by flip-chip mounting) and/or as a platform forpatterning conductive materials (e.g., gold, platinum, palladium,titanium, copper, aluminum, silver, metals, other conductive materials,combinations of these, etc.) to create electrodes, interconnects,antennae, etc. In some embodiments, substantially transparent conductivematerials (e.g., indium tin oxide) may be patterned on substrate 515 toform circuitry, electrodes, etc. For example, antenna 540 may be formedby depositing a pattern of gold or another conductive material onsubstrate 515. Similarly, interconnects 545 and 550 may be formed bydepositing suitable patterns of conductive materials on substrate 515. Acombination of resists, masks, and deposition techniques may be employedto pattern materials on substrate 515. Substrate 515 may be a relativelyrigid material, such as polyethylene terephthalate (“PET”) or anothermaterial sufficient to structurally support the circuitry and/orelectronics within enclosure material 510. Eye-mountable device 500 mayalternatively be arranged with a group of unconnected substrates ratherthan a single substrate. For example, controller 525 and power supply520 may be mounted to one substrate, while antenna 540 and sensor system535 are mounted to another substrate and the two may be electricallyconnected via interconnects.

In some embodiments, power supply 520 and controller 525 (and thesubstrate 515) may be positioned away from the center of eye-mountabledevice 500 and thereby avoid interference with light transmission to theeye through the center of eye-mountable device 510. In contrast,accommodation actuator 530 may be centrally positioned to apply opticalaccommodation to the light transmitted to the eye through the center ofeye-mountable device 510. For example, where eye-mountable device 500 isshaped as a concave-curved disk, substrate 515 may be embedded aroundthe periphery (e.g., near the outer circumference) of the disk. In someembodiments, sensor system 535 includes one or more discrete voltageand/or current sensors that are configured to detect one or morecharacteristics of a magnetic field (not shown) extending at least inpart between EMD 500 and an auxiliary reference device 590 (e.g., one ofdevices 120, 312, 420, 450, 480). For example, sensor system 535 andauxiliary reference device 590 may include some or all of the respectivefeatures of sensor 112 and auxiliary reference device 120. Sensor system535 and/or substrate 515 may be substantially transparent to incomingvisible light to mitigate interference with light transmission to theeye.

Substrate 515 may be shaped as a flattened ring with a radial widthdimension sufficient to provide a mounting platform for the embeddedelectronics components. Substrate 515 may have a thickness sufficientlysmall to allow the substrate to be embedded in enclosure material 510without adversely influencing the profile of eye-mountable device 500.Substrate 515 may have a thickness sufficiently large to providestructural stability suitable for supporting the electronics mountedthereon. For example, substrate 515 may be shaped as a ring with adiameter of about 10 millimeters, a radial width of about 1 millimeter(e.g., an outer radius 1 millimeter larger than an inner radius), and athickness of about 50 micrometers. Substrate 515 may optionally bealigned with the curvature of the eye-mounting surface of eye-mountabledevice 500 (e.g., convex surface). For example, substrate 515 may beshaped along the surface of an imaginary cone between two circularsegments that define an inner radius and an outer radius. In such anexample, the surface of substrate 515 along the surface of the imaginarycone defines an inclined surface that is approximately aligned with thecurvature of the eye mounting surface at that radius.

In the illustrated embodiment, power supply 520 includes a battery 565to power the various embedded electronics, including controller 525.Battery 565 may be inductively charged by charging circuitry 560 andenergy harvesting antenna 555. In one embodiment, antenna 540 and energyharvesting antenna 555 are independent antennae, which serve theirrespective functions of energy harvesting and communications. In anotherembodiment, energy harvesting antenna 555 and antenna 540 are the samephysical antenna that are time shared for their respective functions ofinductive charging and wireless communications with auxiliary device505. Additionally or alternatively, power supply 520 may include a solarcell (“photovoltaic cell”) to capture energy from incoming ultraviolet,visible, and/or infrared radiation. Furthermore, an inertial powerscavenging system may be included to capture energy from ambientvibrations.

Charging circuitry 560 may include a rectifier/regulator to conditionthe captured energy for charging battery 565 or directly powercontroller 525 without battery 565. Charging circuitry 560 may alsoinclude one or more energy storage devices to mitigate high frequencyvariations in energy harvesting antenna 555. For example, one or moreenergy storage devices (e.g., a capacitor, an inductor, etc.) may beconnected to function as a low-pass filter.

Controller 525 contains logic to choreograph the operation of the otherembedded components. Control logic 570 controls the general operation ofeye-mountable device 500, including providing a logical user interface,power control functionality, etc. Accommodation logic 575 includes logicfor monitoring feedback signals from sensor system 535, determining thecurrent gaze direction or gaze distance of the user, and manipulatingaccommodation actuator 530 in response to provide the appropriateaccommodation. The auto-accommodation may be implemented in real-timebased upon feedback from the gaze tracking, or permit user control toselect specific accommodation regimes (e.g., near-field accommodationfor reading, far-field accommodation for regular activities, etc.).Circuitry of controller 525 may include or couple to a repository onsubstrate 515—as represented by the illustrative memory 585 (e.g.,including volatile memory cells)—that, for example, is to store datawritten by such circuitry, data to determine operation of such circuitryand/or data received by (or to be sent from) EMD 500. Such a repositorymay store log information that describes performance of accommodationlogic 575 and/or other components of controller 525.

Communication logic 580 provides communication protocols for wirelesscommunication with auxiliary device 505 via antenna 540. In oneembodiment, communication logic 580 provides backscatter communicationvia antenna 540 when in the presence of an electromagnetic field 571output from auxiliary device 505. In one embodiment, communication logic580 operates as a smart wireless radio-frequency identification (“RFID”)tag that modulates the impedance of antenna 540 for backscatter wirelesscommunications. The various logic modules of controller 525 may beimplemented in software/firmware executed on a general purposemicroprocessor, in hardware (e.g., application specific integratedcircuit), or a combination of both.

Eye-mountable device 500 may include various other embedded electronicsand logic modules. For example, a light source or pixel array may beincluded to provide visible feedback to the user. An accelerometer orgyroscope may be included to provide positional, rotational, directionalor acceleration feedback information to controller 525.

It is noted that the block diagram shown in FIG. 5 is described inconnection with functional modules for convenience in description, butdoes not necessarily connote physical organization. Rather, embodimentsof eye-mountable device 500 may be arranged with one or more of thefunctional modules (“sub-systems”) implemented in a single chip,multiple chips, in one or more integrated circuits, or otherwise.

Auxiliary device 505 includes an antenna 584 (or group of more than oneantennae) to send and receive wireless signals 571 to and fromeye-mountable device 500. Auxiliary device 505 also includes a computingsystem with a processor 582 in communication with a memory 586. Memory586 may be a non-transitory computer-readable medium that may include,without limitation, magnetic disks, optical disks, organic memory,and/or any other volatile (e.g. RAM) or non-volatile (e.g. ROM) storagesystem readable by the processor 582. Memory 586 may include a datastorage 588 to store indications of data, such as data logs (e.g., userlogs), program settings (e.g., to adjust behavior of eye-mountabledevice 500 and/or auxiliary device 505), etc. Memory 586 may alsoinclude program instructions 590 for execution by processor 582 to causethe auxiliary device 505 to perform processes specified by theinstructions 590. For example, program instructions 590 may causeauxiliary device 505 to provide a user interface that allows forretrieving information communicated from eye-mountable device 500 orallows transmitting information to eye-mountable device 500 to programor otherwise select operational modes of eye-mountable device 500.Auxiliary device 505 may also include one or more hardware componentsfor operating antenna 584 to send and receive wireless signals 571 toand from one or both of eye-mountable device 500 and auxiliary referencedevice 590.

Auxiliary device 505 may be a smart phone, digital assistant, or otherportable computing device with wireless connectivity sufficient toprovide the wireless communication link 571. Auxiliary device 505 mayalso be implemented as an antenna module that may be plugged in to aportable computing device, such as in an example where the communicationlink 571 operates at carrier frequencies not commonly employed inportable computing devices. In some instances, auxiliary device 505 is aspecial-purpose device configured to be worn relatively near a wearer'seye to allow the wireless communication link 571 to operate with a lowpower budget. For example, the auxiliary device 505 may be integrated ina piece of jewelry such as a necklace, earing, etc. or integrated in anarticle of clothing worn near the head, such as a hat, headband, etc. Inother embodiments, auxiliary device 505 is a personal computer or gameconsole.

FIGS. 6A and 6B illustrate two views of an eye-mountable device 600, inaccordance with an embodiment of the disclosure. FIG. 6A is a top viewof EMD 600 while FIG. 6B is a perspective view of the same.Eye-mountable device 600 is one possible implementation of eye-mountabledevice 500 illustrated in FIG. 5. The illustrated embodiment ofeye-mountable device 600 includes an enclosure material 610, a substrate615, a power supply 620, a controller 625, an accommodation actuator630, a sensor system 635, and an antenna 640. It should be appreciatedthat FIGS. 6A and 6B are not necessarily drawn to scale, but have beenillustrated for purposes of explanation only in describing thearrangement of the example eye-mountable device 600.

Enclosure material 610 of eye-mountable device 600 may be shaped as acurved disk. Enclosure material 610 is a substantially transparentmaterial to allow incident light to be transmitted to the eye whileeye-mountable device 600 is mounted to the eye. Enclosure material 610may be a biocompatible material similar to those employed to form visioncorrection and/or cosmetic contact lenses in optometry, such as apolymeric material, polyethylene terephthalate (“PET”), polymethylmethacrylate (“PMMA”), polyhydroxyethylmethacrylate (“polyHEMA”), ahydrogel, silicon based polymers (e.g., fluoro-silicon acrylate)combinations of these, or otherwise. Enclosure material 610 may beformed with one side having a concave surface 611 suitable to fit over acorneal surface of an eye. The opposite side of the disk may have aconvex surface 612 that does not interfere with eyelid motion whileeye-mountable device 600 is mounted to the eye. In the illustratedembodiment, a circular or oval outer side edge 613 connects the concavesurface 611 and convex surface 612.

Eye-mountable device 600 may have dimensions similar to a visioncorrection and/or cosmetic contact lenses, such as a diameter ofapproximately 1 centimeter, and a thickness of about 0.1 to about 0.5millimeters. However, the diameter and thickness values are provided forexplanatory purposes only. In some embodiments, the dimensions ofeye-mountable device 600 may be selected according to the size and/orshape of the corneal surface of the wearer's eye. Enclosure material 610may be formed with a curved shape in a variety of ways. For example,techniques similar to those employed to form vision-correction contactlenses, such as heat molding, injection molding, spin casting, etc. maybe employed to form enclosure material 610.

Substrate 615 may be embedded within enclosure material 610. Substrate615 may be embedded to be situated along the outer periphery ofenclosure material 610, away from the central region where accommodationactuator 630 is positioned. In the illustrated embodiment, substrate 615encircles accommodation actuator 630. Substrate 615 may not interferewith vision because it is too close to the eye to be in focus and ispositioned away from the central region where incident light istransmitted to the light-sensing portions of the eye. In someembodiments, substrate 615 may optionally be formed of a transparentmaterial to further mitigate effects on visual perception. Substrate 615may be shaped as a flat, circular ring (e.g., a disk with a centeredhole). The flat surface of substrate 615 (e.g., along the radial width)may be a platform for mounting electronics and for patterning conductivematerials to form electrodes, antenna(e), and/or interconnections.

Sensor system 635 may be distributed about eye-mountable device 600 tosense one or more characteristics of a magnetic field between EMD 600and an auxiliary reference device (not shown) that is remote from EMD600. Such sensing may be used to determine a distance of the remotedevice from EMD 600 and/or a difference between respective orientationsof EMD 600 and the remote device. By monitoring such magnetic fieldcharacteristics, feedback signals from sensor system 635 may be measuredby controller 625 to determine the approximate gaze direction and/orfocal distance. Sensor system 635 may be disposed within enclosurematerial 610 on substrate 615. In the illustrated embodiment, sensorsystem 635 is distributed peripherally around accommodation actuator 630along the inner edge of substrate 615 between antenna 640 andaccommodation actuator 630. In other embodiments, sensor system 635 maybe alternatively distributed in or on eye-mountable device 600.

Accommodation actuator 630 may be centrally positioned within enclosurematerial 610 to affect the optical power of eye-mountable device 600 inthe user's center of vision. In various embodiments, accommodationactuator 630 operates by changing its index of refraction under theinfluence of controller 625. By changing its refractive index, the netoptical power of the curved surfaces of eye-mountable device 600 may bealtered, thereby applying controllable accommodation. Accommodationactuator 630 may be implemented using a variety of differentelectro-active optical devices. For example, accommodation actuator 630may be implemented using a layer of liquid crystal (e.g., a liquidcrystal cell) disposed in the center of enclosure material 610. In otherembodiments, accommodation actuator 630 may be implemented using othertypes of electro-active optical materials such as electro-opticmaterials that vary refractive index in the presence of an appliedelectric field. Accommodation actuator 630 may be a distinct deviceembedded within enclosure material 610 (e.g., liquid crystal cell), or abulk material having a controllable refractive index. In yet anotherembodiment, accommodation actuator 630 may be implemented using adeformable lens structure that changes shape under the influence of anelectrical signal. Accordingly, the optical power of eye-mountabledevice 600 may be controlled by controller 625 with the application ofelectric signals via one or more electrodes extending from controller625 to accommodation actuator 630.

Accommodation actuator 630 may be implemented using a variety ofdifferent liquid crystal structures including nematic liquid crystal,nematic twisted liquid crystal, cholesteric liquid crystal, or bluephase liquid crystal. Since a low switching voltage is desirable for lowpower chip design, nematic liquid crystals with switching voltages lessthan 5 V are suitable. With the application of a 5V control signal,refractive index switching ranging from approximately 1.74 in anoff-mode to 1.52 in an on-mode is achievable. A refractive index shiftof 0.2 should be sufficient to provide near-field accommodation forreading.

Returning to FIG. 6A, loop antenna 640 is a layer of conductive materialpatterned along the flat surface of the substrate to form a flatconductive ring. In some examples, to allow additional flexibility alongthe curvature of the enclosure material, loop antenna 640 may includemultiple substantially concentric sections electrically joined together.Each section may then flex independently along the concave/convexcurvature of eye-mountable device 600. In some examples, loop antenna640 may be formed without making a complete loop. For instances, antenna640 may have a cutout to allow room for controller 625 and power supply620, as illustrated in FIG. 6A. However, loop antenna 640 may also bearranged as a continuous strip of conductive material that wrapsentirely around the flat surface of substrate 615 one or more times. Forexample, a strip of conductive material with multiple windings may bepatterned on the backside of substrate 615 opposite controller 625,power supply 620, and sensor system 635. Interconnects between the endsof such a wound antenna (e.g., the antenna leads) may then be passedthrough substrate 615 to controller 625.

FIG. 7 is a cross-sectional illustration of an eye 715 having implantedtherein an intraocular device 700 that, according to an embodiment,determines a direction of gaze based on an interaction, via a magneticfield, with an auxiliary reference device (not shown). Intraoculardevice 700 may include features of EMD 100 and/or features of one ofophthalmic devices 314, 410, 430, 460, 500, 600, for example.

The illustrated embodiment of intraocular device 700 includes a housing750 and circuitry disposed therein. An exterior of intraocular device700 may include a surface of housing 750 that is biocompatible toaccommodate direct contact with an interior of a human (or other) eye.Such a surface of housing 750 may be formed by one or more materialsthat are both electromagnetically transparent (at least partially) andbiocompatible to accommodate implantation of intraocular device 700.Examples of such materials include, but are not limited to, any ofvarious biocompatible hydrogels, silicones, hydrophobic acrylics,fluorinated polymethacrylates and/or the like. In an embodiment, housing750 includes a coating of biocompatible material that, for example, isformed by atomic layer deposition. Such materials may be adapted fromthose used in existing intraocular devices, for example.

Intraocular device 700 may be implanted into the anterior chamber, theposterior chamber, or other locations of a user's eye. Intraoculardevice 700 is illustrated as being implanted within the posteriorchamber 705 behind an iris 710 of eye 715. However, intraocular device700 may be implanted into other locations, as well, such as anteriorchamber 720 disposed between iris 710 and cornea 725. In an embodiment,intraocular device 700 includes a housing 750 and circuitry 760 disposedin or on housing 750. Circuitry 760 may enable device 700 to interactvia a magnetic field with an auxiliary reference device (not shown) thatis in or on the body of the user of intraocular device 700. For example,circuitry 760 may be disposed at a side 752 of housing 750 that facestoward cornea 725—e.g., to sense a magnetic field (not shown) extendingin posterior chamber 705. In an embodiment, circuitry 760 includes oneor more magnetic sensors to detect one or more characteristics of such amagnetic field. Alternatively or in addition, such one or more magneticsensors may detect a voltage and/or a current that is based on operationof other circuitry (included in or coupled to circuitry 760) that, forexample, may generate at least part of such a magnetic field.

The processes explained above are described in terms of computersoftware and hardware. The techniques described may constitutemachine-executable instructions embodied within a tangible ornon-transitory machine (e.g., computer) readable storage medium, thatwhen executed by a machine will cause the machine to perform theoperations described. Additionally, the processes may be embodied withinhardware, such as an application specific integrated circuit (“ASIC”) orotherwise.

A tangible machine-readable storage medium includes any mechanism thatprovides (i.e., stores) information in a non-transitory form accessibleby a machine (e.g., a computer, network device, personal digitalassistant, manufacturing tool, any device with a set of one or moreprocessors, etc.). For example, a machine-readable storage mediumincludes recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, etc.).

The above description of illustrated embodiments of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. An ophthalmic system comprising: a magnetic fieldgenerator disposed within an enclosure of an ophthalmic device andconfigured to generate a magnetic field which extends beyond theophthalmic device to interact with an auxiliary reference deviceexternal to the ophthalmic device; a sensor disposed within theenclosure and coupled to the magnetic field generator to measure amagnetic field interaction with the auxiliary reference device as a loadon the magnetic field generator, wherein the sensor is furtherconfigured to generate a magnetic field signal based on the magneticfield interaction; an accommodation lens disposed within the enclosure;and a controller disposed within the enclosure and coupled to the sensorand the accommodation lens, wherein the controller includes logic thatwhen executed by the controller causes the controller to performoperations including: monitoring the magnetic field signal; andcorrelating the magnetic field signal to a gazing direction of theophthalmic device.
 2. The ophthalmic system of claim 1, wherein thecontroller includes further logic that when executed by the controllercauses the controller to perform further operations including:detecting, in real-time, changes in the gazing direction of theophthalmic device based upon changes in the magnetic field signal; andelectrically manipulating the accommodation lens to automatically changean optical power of the ophthalmic device in response to detectingchanges in the magnetic field signal.
 3. The ophthalmic system of claim1, wherein the auxiliary reference device comprises a passive circuitthat passively loads the magnetic field.
 4. The ophthalmic system ofclaim 1, wherein the auxiliary reference device is configured to beimplanted under a surface of skin of a user.
 5. The ophthalmic system ofclaim 1, wherein the auxiliary reference device comprises an activecircuit that is powered by the magnetic field from the ophthalmic deviceand presents a modulated load on the magnetic field.
 6. The ophthalmicsystem of claim 1, wherein the controller further comprises logic thatwhen executed by the controller causes the controller to perform furtheroperations comprising: modulating the magnetic field to induce the loadon the magnetic field generator.
 7. The ophthalmic system of claim 1,wherein the magnetic field generator comprises an electromagnet circuitincluding a conductor which extends around the accommodation lens.
 8. Anophthalmic system comprising: one or more magnetic sensors disposedwithin an enclosure of an ophthalmic device, the one or more magneticsensors configured to measure magnetic field interactions with aplurality of auxiliary reference devices disposed external to theophthalmic device, the one or more magnetic sensors further configuredto generate magnetic field signals based on the magnetic fieldinteractions; an accommodation lens disposed within the enclosure; and acontroller disposed within the enclosure and coupled to the magneticsensors and the accommodation lens, wherein the controller includeslogic that when executed by the controller causes the controller toperform operations including: measuring, with the one or more magneticsensors, the magnetic field interactions between the ophthalmic deviceand the auxiliary reference devices external to the ophthalmic device;generating, with the one or more magnetic sensors, the magnetic fieldsignals based on the magnetic field interactions; and correlating acombination of the magnetic field signals from the plurality ofauxiliary reference devices to a gazing direction.
 9. The ophthalmicsystem of claim 8, wherein measuring the magnetic field interactionsincludes: detecting a first magnetic field modulation signature of afirst one of the auxiliary reference device; and detecting a secondmagnetic field modulation signature of a second one of the auxiliaryreference devices, wherein the first and second magnetic fieldmodulations signatures enables the ophthalmic device to distinguishbetween the magnetic field interactions with the plurality of auxiliaryreference devices for triangulation of a position or an orientation ofthe ophthalmic device relative to the plurality of auxiliary referencedevices.
 10. The ophthalmic system of claim 8, wherein the enclosureincludes: a concave surface; and a convex surface; wherein the concavesurface is configured to be removeably mounted over a cornea and theconvex surface is configured to be compatible with eyelid motion whenthe concave surface is so mounted.
 11. The ophthalmic system of claim 8,wherein the ophthalmic device comprises an intraocular device.
 12. Theophthalmic system of claim 8, wherein the magnetic sensors comprise Halleffect sensors.
 13. A method at an ophthalmic device, the methodcomprising: generating a first magnetic field with a magnetic fieldgenerator disposed in or on the ophthalmic device; measuring a firstmagnetic field interaction between the ophthalmic device and a firstauxiliary reference device external to the ophthalmic device as a loadimparted by the first auxiliary reference device onto the magnetic fieldgenerator via the first magnetic field, the first magnetic fieldinteraction occurring while the first auxiliary reference device isadhered on or disposed under a surface of skin of a user; generating afirst one or more magnetic field signals in response to the measuringthe first magnetic field interaction; correlating the first one or moremagnetic field signals to a gazing direction of a cornea upon which theophthalmic device is mounted or in which the ophthalmic device isdisposed; detecting, in real-time, changes in the gazing direction basedupon changes in the first one or more magnetic field signals; andelectrically manipulating an accommodation lens of the ophthalmic deviceto automatically change an optical power of the ophthalmic device inresponse to detecting changes in the gazing direction.
 14. The method ofclaim 13, wherein the first auxiliary reference device comprises apassive circuit that passively loads the first magnetic field, the firstauxiliary reference device positioned peripherally to an eye whichincludes the cornea.
 15. The method of claim 13, wherein the ophthalmicdevice comprises an enclosure having a concave surface and a convexsurface, wherein the concave surface is removeably mounted over thecornea.
 16. The method of claim 13, wherein measuring the first magneticfield interaction comprises measuring with one or more Hall effectsensors disposed within an enclosure of the ophthalmic device.
 17. Themethod of claim 13, wherein the magnetic field generator comprises anelectromagnet circuit of the ophthalmic device.
 18. The method of claim17, further comprising: modulating the first magnetic field to inducethe load on the electromagnet circuit.
 19. The method of claim 17,wherein the electromagnet circuit comprises a conductor which extendsaround the accommodation lens.
 20. The method of claim 17, wherein thegenerating the first magnetic field includes powering a modulation ofthe first magnetic field by the first auxiliary reference device. 21.The method of claim 13, further comprising: measuring a second magneticfield interaction between the ophthalmic device and a second auxiliaryreference device external to the ophthalmic device; and generating asecond one or more magnetic field signals based on the second magneticfield interaction; wherein the correlating the first one or moremagnetic field signals to the gazing direction includes correlating acombination of the first one or more magnetic field signals and thesecond one or more magnetic field signals to the gazing direction. 22.The method of claim 21, wherein measuring the first magnetic fieldinteraction includes detecting a first magnetic field modulationsignature of the first auxiliary reference device, and wherein measuringthe second magnetic field interaction includes detecting a secondmagnetic field modulation signature of the second auxiliary referencedevice.